LXR linux/include/linux/sunrpc/cache.h

   1/*
   2 * include/linux/sunrpc/cache.h
   3 *
   4 * Generic code for various authentication-related caches
   5 * used by sunrpc clients and servers.
   6 *
   7 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
   8 *
   9 * Released under terms in GPL version 2.  See COPYING.
  10 *
  11 */
  12
  13#ifndef _LINUX_SUNRPC_CACHE_H_
  14#define _LINUX_SUNRPC_CACHE_H_
  15
  16#include <linux/kref.h>
  17#include <linux/slab.h>
  18#include <linux/atomic.h>
  19#include <linux/proc_fs.h>
  20
  21/*
  22 * Each cache requires:
  23 *  - A 'struct cache_detail' which contains information specific to the cache
  24 *    for common code to use.
  25 *  - An item structure that must contain a "struct cache_head"
  26 *  - A lookup function defined using DefineCacheLookup
  27 *  - A 'put' function that can release a cache item. It will only
  28 *    be called after cache_put has succeed, so there are guarantee
  29 *    to be no references.
  30 *  - A function to calculate a hash of an item's key.
  31 *
  32 * as well as assorted code fragments (e.g. compare keys) and numbers
  33 * (e.g. hash size, goal_age, etc).
  34 *
  35 * Each cache must be registered so that it can be cleaned regularly.
  36 * When the cache is unregistered, it is flushed completely.
  37 *
  38 * Entries have a ref count and a 'hashed' flag which counts the existence
  39 * in the hash table.
  40 * We only expire entries when refcount is zero.
  41 * Existence in the cache is counted  the refcount.
  42 */
  43
  44/* Every cache item has a common header that is used
  45 * for expiring and refreshing entries.
  46 * 
  47 */
  48struct cache_head {
  49        struct hlist_node       cache_list;
  50        time_t          expiry_time;    /* After time time, don't use the data */
  51        time_t          last_refresh;   /* If CACHE_PENDING, this is when upcall was
  52                                         * sent, else this is when update was
  53                                         * received, though it is alway set to
  54                                         * be *after* ->flush_time.
  55                                         */
  56        struct kref     ref;
  57        unsigned long   flags;
  58};
  59#define CACHE_VALID     0       /* Entry contains valid data */
  60#define CACHE_NEGATIVE  1       /* Negative entry - there is no match for the key */
  61#define CACHE_PENDING   2       /* An upcall has been sent but no reply received yet*/
  62#define CACHE_CLEANED   3       /* Entry has been cleaned from cache */
  63
  64#define CACHE_NEW_EXPIRY 120    /* keep new things pending confirmation for 120 seconds */
  65
  66struct cache_detail {
  67        struct module *         owner;
  68        int                     hash_size;
  69        struct hlist_head *     hash_table;
  70        rwlock_t                hash_lock;
  71
  72        char                    *name;
  73        void                    (*cache_put)(struct kref *);
  74
  75        int                     (*cache_upcall)(struct cache_detail *,
  76                                                struct cache_head *);
  77
  78        void                    (*cache_request)(struct cache_detail *cd,
  79                                                 struct cache_head *ch,
  80                                                 char **bpp, int *blen);
  81
  82        int                     (*cache_parse)(struct cache_detail *,
  83                                               char *buf, int len);
  84
  85        int                     (*cache_show)(struct seq_file *m,
  86                                              struct cache_detail *cd,
  87                                              struct cache_head *h);
  88        void                    (*warn_no_listener)(struct cache_detail *cd,
  89                                              int has_died);
  90
  91        struct cache_head *     (*alloc)(void);
  92        int                     (*match)(struct cache_head *orig, struct cache_head *new);
  93        void                    (*init)(struct cache_head *orig, struct cache_head *new);
  94        void                    (*update)(struct cache_head *orig, struct cache_head *new);
  95
  96        /* fields below this comment are for internal use
  97         * and should not be touched by cache owners
  98         */
  99        time_t                  flush_time;             /* flush all cache items with
 100                                                         * last_refresh at or earlier
 101                                                         * than this.  last_refresh
 102                                                         * is never set at or earlier
 103                                                         * than this.
 104                                                         */
 105        struct list_head        others;
 106        time_t                  nextcheck;
 107        int                     entries;
 108
 109        /* fields for communication over channel */
 110        struct list_head        queue;
 111
 112        atomic_t                readers;                /* how many time is /chennel open */
 113        time_t                  last_close;             /* if no readers, when did last close */
 114        time_t                  last_warn;              /* when we last warned about no readers */
 115
 116        union {
 117                struct proc_dir_entry   *procfs;
 118                struct dentry           *pipefs;
 119        };
 120        struct net              *net;
 121};
 122
 123
 124/* this must be embedded in any request structure that
 125 * identifies an object that will want a callback on
 126 * a cache fill
 127 */
 128struct cache_req {
 129        struct cache_deferred_req *(*defer)(struct cache_req *req);
 130        int thread_wait;  /* How long (jiffies) we can block the
 131                           * current thread to wait for updates.
 132                           */
 133};
 134/* this must be embedded in a deferred_request that is being
 135 * delayed awaiting cache-fill
 136 */
 137struct cache_deferred_req {
 138        struct hlist_node       hash;   /* on hash chain */
 139        struct list_head        recent; /* on fifo */
 140        struct cache_head       *item;  /* cache item we wait on */
 141        void                    *owner; /* we might need to discard all defered requests
 142                                         * owned by someone */
 143        void                    (*revisit)(struct cache_deferred_req *req,
 144                                           int too_many);
 145};
 146
 147/*
 148 * timestamps kept in the cache are expressed in seconds
 149 * since boot.  This is the best for measuring differences in
 150 * real time.
 151 */
 152static inline time_t seconds_since_boot(void)
 153{
 154        struct timespec boot;
 155        getboottime(&boot);
 156        return get_seconds() - boot.tv_sec;
 157}
 158
 159static inline time_t convert_to_wallclock(time_t sinceboot)
 160{
 161        struct timespec boot;
 162        getboottime(&boot);
 163        return boot.tv_sec + sinceboot;
 164}
 165
 166extern const struct file_operations cache_file_operations_pipefs;
 167extern const struct file_operations content_file_operations_pipefs;
 168extern const struct file_operations cache_flush_operations_pipefs;
 169
 170extern struct cache_head *
 171sunrpc_cache_lookup(struct cache_detail *detail,
 172                    struct cache_head *key, int hash);
 173extern struct cache_head *
 174sunrpc_cache_update(struct cache_detail *detail,
 175                    struct cache_head *new, struct cache_head *old, int hash);
 176
 177extern int
 178sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
 179
 180
 181extern void cache_clean_deferred(void *owner);
 182
 183static inline struct cache_head  *cache_get(struct cache_head *h)
 184{
 185        kref_get(&h->ref);
 186        return h;
 187}
 188
 189
 190static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
 191{
 192        if (kref_read(&h->ref) <= 2 &&
 193            h->expiry_time < cd->nextcheck)
 194                cd->nextcheck = h->expiry_time;
 195        kref_put(&h->ref, cd->cache_put);
 196}
 197
 198static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
 199{
 200        if (!test_bit(CACHE_VALID, &h->flags))
 201                return false;
 202
 203        return  (h->expiry_time < seconds_since_boot()) ||
 204                (detail->flush_time >= h->last_refresh);
 205}
 206
 207extern int cache_check(struct cache_detail *detail,
 208                       struct cache_head *h, struct cache_req *rqstp);
 209extern void cache_flush(void);
 210extern void cache_purge(struct cache_detail *detail);
 211#define NEVER (0x7FFFFFFF)
 212extern void __init cache_initialize(void);
 213extern int cache_register_net(struct cache_detail *cd, struct net *net);
 214extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
 215
 216extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
 217extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
 218
 219extern void sunrpc_init_cache_detail(struct cache_detail *cd);
 220extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
 221extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
 222                                        umode_t, struct cache_detail *);
 223extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
 224extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
 225
 226/* Must store cache_detail in seq_file->private if using next three functions */
 227extern void *cache_seq_start(struct seq_file *file, loff_t *pos);
 228extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos);
 229extern void cache_seq_stop(struct seq_file *file, void *p);
 230
 231extern void qword_add(char **bpp, int *lp, char *str);
 232extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
 233extern int qword_get(char **bpp, char *dest, int bufsize);
 234
 235static inline int get_int(char **bpp, int *anint)
 236{
 237        char buf[50];
 238        char *ep;
 239        int rv;
 240        int len = qword_get(bpp, buf, sizeof(buf));
 241
 242        if (len < 0)
 243                return -EINVAL;
 244        if (len == 0)
 245                return -ENOENT;
 246
 247        rv = simple_strtol(buf, &ep, 0);
 248        if (*ep)
 249                return -EINVAL;
 250
 251        *anint = rv;
 252        return 0;
 253}
 254
 255static inline int get_uint(char **bpp, unsigned int *anint)
 256{
 257        char buf[50];
 258        int len = qword_get(bpp, buf, sizeof(buf));
 259
 260        if (len < 0)
 261                return -EINVAL;
 262        if (len == 0)
 263                return -ENOENT;
 264
 265        if (kstrtouint(buf, 0, anint))
 266                return -EINVAL;
 267
 268        return 0;
 269}
 270
 271static inline int get_time(char **bpp, time_t *time)
 272{
 273        char buf[50];
 274        long long ll;
 275        int len = qword_get(bpp, buf, sizeof(buf));
 276
 277        if (len < 0)
 278                return -EINVAL;
 279        if (len == 0)
 280                return -ENOENT;
 281
 282        if (kstrtoll(buf, 0, &ll))
 283                return -EINVAL;
 284
 285        *time = (time_t)ll;
 286        return 0;
 287}
 288
 289static inline time_t get_expiry(char **bpp)
 290{
 291        time_t rv;
 292        struct timespec boot;
 293
 294        if (get_time(bpp, &rv))
 295                return 0;
 296        if (rv < 0)
 297                return 0;
 298        getboottime(&boot);
 299        return rv - boot.tv_sec;
 300}
 301
 302#endif /*  _LINUX_SUNRPC_CACHE_H_ */
 303